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Has anyone experienced a swishing sound behind the dash around the glove compartment area when just starting out in first or reversing at slow speeds? I'm not very technically savvy so this may be an obvious question but it sounds alot like a humidifier or water swishing around. Anyone know what that could be?
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Is your AC on when you hear it? If so you are probably hearing the AC evaporator. Its like a little radiator in your dash. The AC compressor compresses the R134a gas into a liquid that is then cooled by the condenser (AC radiator on the front of your car) and then flows into the evaporator.
In the evaporator the liquid passes through small nozzle that has lower pressure on the other side. Therefore, when the liquid R134a pass through it, it turns into a gas that absorbs heat i.e. is cold. The process is similar to spraying a spray can for a long time. If you have ever have, the can gets cold. Ice will even form on the outside. Try spraying some canned air into a computer for a few minutes—you’ll freeze you hand off The releasing of the pressurized R134a liquid into a gas can make a hissing or swishing sound. And off idle it can be noticeable because there is less engine noise and you hear the pressure and noise from it increase as your engine RPM increases off idle.
The other thing it could be is your heater core. It's another little radiator under your dash that warm engine coolant is circulated through. While I haven't heard it on the 8, sometimes an air bubble gets trapped in there and contributes to making a bubbling/water flowing noise. Also, if the heater is part way on, then the hot coolant can sometimes make a noise as it squeezes through the heater valve just like when you turn down the water on a faucet in your house and it makes a noise. However, unlike you house, the pressure through this valve varies with engine RPM. To find out, try turning the heater **** up and down when you hear the noise. Oh, and don't forget your AC is on if any form of defrost is on or floor heat is on by itself. Seriously When is the A/C Compressor Running?
Hope this helps
Last edited by RotaMotion; 01-05-2005 at 01:48 AM.
Someone posted this exact same question the other day in one of the other sections...I believe this is caused by air caught in the coolant, or something like that. It's not disatrous, but neither is it good for the car. I'd mention it to the dealer to see if they can do something about it.
Air in the coolant is not a very good thing, and it can lead to uneven overheating in the engine. If you are hearing swishing, then I would take it to the dealer and have them bleed the coolant system. The RX 8 is not the easiest car to bleed air out of so it might be that it wasn't done quite right. I am less convinced by the AC theory just because I have heard several people complain about air in the coolant, but none have really complained about a swishing noise from AC cycling. Anyway, get it checked. It isn't a good thing.
Location: Lake in the Hills, IL (NW Chicago Burbs)
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It's definitely air trapped in the cooling system, in the heater core behind the dash to be specific. Every '8 I've been in has had this to some extent... it can be bled out if you really want, but it's not a major concern.
It's definitely air trapped in the cooling system, in the heater core behind the dash to be specific. Every '8 I've been in has had this to some extent... it can be bled out if you really want, but it's not a major concern.
That's what I like. Remote, definitive diagnosis of a problem. You gotta be kidding me.
i had the same problem on my CRX what happened is the drain to the ac got stopped up and eventually it started dumping water on my floor .so turn your ac on and make sure it is draining. hope this helps
I have this sound too. It's water running through the hearter core in the middle of the dash. Not sure what causes it. It's pretty rare but I have had it happen. In talking with Mazcare in Atlanta, the 3rd gen car had the issue also and there was a small valve that was installed in the water flow line somewhere to correct. Not sure is Mazda is aware of this or has a fix on the way......
The releasing of the pressurized R134a liquid into a gas can make a hissing or swishing sound. And off idle it can be noticeable because there is less engine noise and you hear the pressure and noise from it increase as your engine RPM increases off idle.
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